Motorized rotary lawn mowers, as opposed to reel mowers, generally have a shrouded housing within which an elongate rectangular steel blade with sharpened leading edges rotates on a vertical drive shaft. The blade is connected to the drive shaft by means of a threaded fastener. The blade needs service, such as sharpening or balancing, from time to time. Such service is best performed by first removing the blade from the drive shaft.
The removal of blade from the drive shaft is most safely performed by first protecting the operator from injury due to contact with the sharpened leading edges. The operator can protect himself by donning heavy gloves but this may make normal operations, such as adjusting and applying a wrench, more difficult. Alternatively, it is known to place protective sheaths around the opposite ends of the blade, one such arrangement being illustrated in U.S. Pat. No. 4,306,600 issued Dec. 22, 1981 to Charles Lonsinger, Jr. The Lonsinger device comprises two separate stitched sheaths which are interconnectable by means of a strap with snaps.